Abstract: A fail-safe lighting system which includes provision for setting priorities or sequences of operation for different lights or sets of lights. When normal power is interrupted, all or a selected number of lights remain lit and/or are dimmed, thus providing a first level of illumination during a predetermined period of time. However, when a selected interval of time has elapsed and the level of charge remaining on the battery or batteries which supply power during the interruption decreases, preselected one or ones of the lights are progressively dimmed or disconnected from the battery acccording to a predetermined schedule. Thus, the time during which one or more extremely critical lights remain lit can be substantially extended without depleting the charge on the battery.